Elastic crawler traveling apparatus and sprocket for crawler belt used in the same

ABSTRACT

An elastic crawler traveling apparatus having an elastic crawler in a shape of an endless belt, a sprocket for a crawler belt arranged to be brought into contact with an inner face of the elastic crawler, a driven wheel, and a rolling wheel, the elastic crawler including a belt main body, a plurality of projections formed to project at intervals along a peripheral direction on an inner face of the belt main body, and a tension member embedded at an inner portion of the belt main body for restricting elongation of the belt main body, in which the sprocket has a contact portion to contact the belt main body and a contact width of the contact portion in a belt width direction of the elastic crawler is wider than a root width of the projection in the belt width direction.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an elastic crawler travelingapparatus used for traveling, for example, on a soft ground inconstruction, civil engineering, agriculture or the like and a sprocketfor a crawler belt used in the elastic crawler traveling apparatus.

[0003] 2. Description of the Prior Art

[0004] An elastic crawler traveling apparatus having an elastic crawlerformed by an elastic material of rubber or the like is currently usedwidely in an agricultural machine such as a combine and a constructionoperation machine such as a back hoe.

[0005] Conventionally, the elastic crawler traveling apparatus is mainlyconstituted by an elastic crawler formed in a shape of an endless belt,a sprocket for a crawler belt to be brought into contact with an innerface of the elastic crawler, a driven wheel, and a rolling wheel.

[0006] The sprocket for the crawler belt, the driven wheel and therolling wheel are arranged at predetermined center distancestherebetween and the elastic crawler can be circulatingly run by atransmission of driving force by the sprocket for the crawler belt.

[0007] An explanation will be given as follows of the elastic crawlerand the sprocket for the crawler belt, the driven wheel and the rollingwheel in reference to FIG. 13 through FIG. 15.

[0008]FIG. 13 shows a state in which an elastic crawler and a sprocketfor a crawler belt are brought into contact with each other.

[0009] An elastic crawler 42 shown in FIG. 13 is mainly constituted by abelt main body 47 in a shape of an endless belt, a plurality ofprojections 48 formed to project from an inner face of the belt mainbody 47 and a tension member 49 of a steel cord or the like embedded atan inner portion of the belt main body 47 for restricting elongation ofthe belt main body 47.

[0010] A plurality of the projections 48 are arranged at constantintervals over an entire periphery of the inner face of the belt mainbody 47.

[0011] The tension member 49 is provided for restricting elongationcaused by an outwardly pushing force (hereinafter, referred to asextending tension force) exerted by a sprocket 43 for a crawler belt,the driven wheel 45 and the rolling wheel 46 to extend the elasticcrawler 42 on the inner face of the elastic crawler 42.

[0012] A plurality of the tension members 49 are embedded within aconstant embedding width (width designated by notation A, hereinafter,referred to as embedding width A) in a belt width direction (directionindicated by notation X, hereinafter, the direction is defined as areference direction and the direction is simply referred to as beltwidth direction) of the belt main body 47.

[0013] The sprocket 43 for a crawler belt for driving the elasticcrawler 42 is constituted by a drive tooth portion 51 in a rod-likeshape fitted to a valley portion between the projections 48 fortransmitting the driving force to the elastic crawler 42 and a pair ofbarrel portion main bodies 50 in a shape of a circular disk forsandwiching the drive tooth portion 51.

[0014] As shown by FIG. 13, a length of the drive tooth portion 51 in alongitudinal direction thereof and a root width (width indicated bynotation D) of the projection 48 in the belt width direction are made tobe substantially equal to each other and the barrel portion main bodies50 are disposed so as to sandwich the drive tooth portion 51therebetween.

[0015] A contact width in the belt width direction of a portion 56 ofthe sprocket 43 for the crawler belt in contact with the inner face ofthe crawler main body 47 is constituted by adding the length in thelongitudinal direction of the drive tooth portion 51 and widths in thebelt width direction of the barrel portion main bodies 50, and thecontact width is indicated by notation E (hereinafter, the width isreferred to as contact width E in the sprocket 43 of the crawler belt).

[0016] When the length in the longitudinal direction of the drive toothportion 51 and the root width of the projection 48 are made to besubstantially equal to each other as described above, and the drivetooth portion 51 are sandwiched by the barrel portion main bodies 50, inthe case in which the elastic crawler 42 and the sprocket 43 for thecrawler belt are shifted from each other in the belt width direction, aface on an inner side of the barrel portion main body 50 is brought intocontact with the projection 48 to thereby enable to restrict the shiftof the sprocket 43 for the crawler belt.

[0017] However, since a thickness (a width in the belt width direction)of the drive portion main body 50 is made to be as small as possible forlight-weighted formation of the sprocket 43 for the crawler belt and areduction in material cost, the contact width E in the sprocket 43 forthe crawler belt is made smaller than the embedding width A.

[0018] A difference between the contact width E of the sprocket 43 forthe crawler belt and the embedding width A is indicated by notation F,which is hereinafter referred to as a noncontact width F.

[0019]FIG. 14 shows a state in which the driven wheel 45 or the rollingwheel 46 and the belt main body 47 are brought into contact with eachother.

[0020] In FIG. 14, either of the driven wheel 45 and the rolling wheel46 constitutes a so-to-speak riding rolling wheel which rolls on aninner peripheral face of the belt main body 47 by riding over theprojection 48. A contact width of a portion of the driven wheel 45 (orrolling wheel 46) in contact with the inner face of the belt main body47 in the belt width direction is indicated by notation G (hereafter,referred to as contact width G in the driven wheel or the like).

[0021] Further, in FIG. 14, the contact width E of the sprocket 43 forthe crawler belt is shown for comparison.

[0022] When the contact width E of the sprocket 43 for the crawler beltis compared with the contact width G of the driven wheel or the like,the contact width E of the sprocket 43 for the crawler belt and thecontact width G of the driven wheel or the like are not completelycoincident with each other although there are coincident portionsthereof.

[0023] In this case, the tension member 49 disposed in a range in whichthe contact width E of the sprocket 43 for the crawler belt and thecontact width G of the driven wheel or the like are coincident with eachother (overlap each other) (hereinafter, referred to as coincidentrange) undergoes the extending tension force from the sprocket 43 forthe crawler belt, the driven wheel 45 and the rolling wheel 46. However,the tension member 49 disposed outside of the coincident range undergoesthe extending tension force only from the sprocket 43 for the crawlerbelt or only from the driven wheel or the like.

[0024]FIG. 15 is a sectional view taken along arrow marks Q-Q of FIG.13, showing a state in which the elastic crawler 42 is wrapped aroundthe sprocket 43 for the crawler belt.

[0025] The elastic crawler 42 is mounted around the sprocket 43 for thecrawler belt with being pulled (being applied with tension) in aperipheral direction (direction indicated by notation Y) of the elasticcrawler 42 (belt main body 8).

[0026] In this case, the rate of elongation caused by the pulling forcediffers between a portion of the belt main body 47 formed with theprojection 48 and a portion thereof between the projections 48.

[0027] More specifically, the portion provided with the projection isdifficult to elongate since the thickness of the belt main body 47 isthicker by an amount of the projection, while the portion of the beltmain body 8 between the projections 48 is readily elongated.

[0028] Therefore, when tension is applied along the peripheral directionof the elastic crawler 2, a portion of the tension member 49 which isreadily elongated (portion between the projections 9) is pulled to belinear to thereby constitute a form in which the linear portions areconnected at the portion difficult to elongate. Accordingly, as shown byFIG. 15, the tension member 49 is deformed into a polygonal shape.

[0029] When the tension member 49 disposed in the coincident range iscompared with the tension member 49 disposed outside of the coincidentrange as described above, the tension member 49 disposed in thecoincident range undergoes the extending tension force at a plurality ofportions by the sprocket for the crawler belt, the driven wheel, and therolling wheel. Accordingly, a total of the tension member 49 disposed inthe coincident range undergoes substantially uniform force, while thetension member 49 disposed outside of the coincident range undergoeslocal tension force only by the sprocket for the crawler belt or only bythe driven wheel 45 (or the rolling wheel 46).

[0030] There poses a problem that when the tension member 49 undergoeslocal tension force as in the tension member 49 disposed outside of thecoincident range as described above, the portion undergoing the tensionforce is liable to break.

[0031] Further, since the sprocket 43 for the crawler belt is notbrought into contact with the inner face portion of the belt main body47 (elastic crawler) corresponding to the noncontact width F, theportion is hardly exerted with tension force, whereby the tension forceexerted on the tension member 49 disposed within the contact width E inthe sprocket for the crawler belt and the tension force exerted on thetension member 49 disposed in the noncontact width F are not uniform.

[0032] In this case, the tension member exerted with a greater tensionforce (tension member disposed in the contact width E of the sprocketfor the crawler belt) is liable to break and service life thereof isalso shortened.

[0033] This is a problem caused by making the length in the longitudinaldirection of the drive tooth portion substantially equal to the rootwidth of the projection.

[0034] Further, when the tension member 49 is deformed into thepolygonal shape, there poses a problem that local tension force isexerted on a portion of a corner in the polygonal shape and the portionis broken.

[0035] This is a problem caused by local application of the tensionforce on the tension member 49.

[0036] Hence, it is an object of the invention to provide an elasticcrawler traveling apparatus capable of making exertion of local force toa tension member embedded in an elastic member as less as possible, anda sprocket for a crawler belt used in the elastic crawler drivingapparatus.

[0037] It is an another object of the invention to provide a sprocketfor a crawler belt capable of exerting uniform extension force to awrapping portion of a tension member embedded in an elastic crawler.

SUMMARY OF THE INVENTION

[0038] According to an aspect of the invention, there is provided anelastic crawler traveling apparatus 1 including an elastic crawler 2 ina shape of an endless belt formed by an elastic material of rubber orthe like; a sprocket 3 for a crawler belt arranged to be brought intocontact with an inner face of the elastic crawler 2; a driven wheel 6;and a rolling wheel 7, wherein the elastic crawler 2 comprising a beltmain body 8, a plurality of projections 9 formed to project at intervalstherebetween along a peripheral direction on an inner face of the beltmain body 8, and a tension member 14 of a steel cord or the likeembedded at an inner portion of the belt main body 8 for restrictingelongation of the belt main body 8, and wherein the sprocket 3 for thecrawler belt includes a contact portion 17 in contact with the belt mainbody 8 having a contact width in the belt width direction which is widerthan a root width B of the projection 9 in the belt width direction.

[0039] Since the range of coincidence can be widened by an amount ofwidening the contact width in the sprocket of the crawler belt relativeto the root width in the belt width direction of the projection,exertion of local force to the tension member can be made as less aspossible.

[0040] According to another aspect of the invention, there is providedan elastic crawler traveling apparatus 1 including an elastic crawler 2in a shape of an endless belt formed by an elastic material of rubber orthe like; a sprocket 3 for a crawler belt arranged to be brought intocontact with an inner face of the elastic crawler 2; a driven wheel 6;and a rolling wheel 7, wherein the elastic crawler 2 comprising a beltmain body 8, a plurality of projections 9 formed to project at intervalstherebetween along a peripheral direction on an inner face of the beltmain body 8, and a tension member 14 of a steel cord or the likeembedded at an inner portion of the belt main body 8 for restrictingelongation of the belt main body 8, and wherein the sprocket 3 for thecrawler belt includes a contact portion 17 in contact with the belt mainbody 8 having a contact width in the belt width direction which issubstantially equal to an embedding width of the tension member 14 inthe belt width direction.

[0041] With this arrangement, the tension member in a portion of theelastic crawler wrapped around the sprocket for the crawler belt can beexerted with uniform extending tension force.

[0042] According to another aspect of the invention, the sprocket forthe crawler belt comprises a plurality of drive tooth portions 12 to beengaged with the projections 9 and a barrel portion main body 10integrally formed with the drive tooth portions 12 and a portion of thebarrel portion main body 10 between the drive tooth portions 12 isformed with a recessed portion 11 for preventing a projected end portionof the projection 9 and the barrel portion main body 10 from beingbrought into contact with each other.

[0043] At an engaging portion (wrapping portion) of the elastic crawlerand the sprocket for the crawler belt, the drive tooth portion isdisposed between the projections, in other words, the projection isdisposed between the drive tooth portions.

[0044] By providing such a recessed portion, a clearance is producedbetween the drive tooth portions and the projections and, therefore,soil (mud) or the like becomes difficult to be stuck on the barrelportion main body and the soil (mud) or the like is easily discharged.

[0045] According to another aspect of the invention, the sprocket 3 forthe crawler belt comprises a plurality of drive tooth portions 12 to beengaged with the projections 9 and a barrel portion main body 10integrally formed with the drive tooth portions 12. Each pair of theprojections 9 adjacent in the peripheral direction of the elasticcrawler form a valley portion therebetween as an engaging groove 15 tobe engaged with the drive tooth portion 12. The drive tooth portion 12comprises a driving portion 18 to be engaged with the engaging groove15, and a guide portion 19 to be engaged with the projection 9 in thebelt width direction for restricting a shift of the drive tooth portion12 and the projection 9 in the belt width direction relative to eachother.

[0046] This arrangement can restrict a shift of the sprocket for thecrawler belt relative to the elastic crawler in the belt width directionand a disengagement of sprocket for the crawler belt from the elasticcrawler.

[0047] According to another aspect of the invention, the sprocket 3 forthe crawler belt comprises a drive tooth portion 12 in a rod-like shapeto be engaged with the projection 9, and a pair of barrel portion mainbodies 10 having a cylindrical shape and sandwiching the drive toothportion 12 therebetween, and the barrel main body 10 defines along itsperipheral portion a plurality of mud discharging holes 27 fordischarging soil, mud or the like.

[0048] This arrangement improves mud discharging performance of thesprocket for the crawler belt.

[0049] The drive tooth portion 12 has opposite ends in the longitudinaldirection thereof each of which is brought into contact with andintegrated with each of the pair of barrel portion main body 10 on aside edge in the widthwise direction thereof facing its counterpart mainbody 10. A plurality of the drive tooth portions 12 are arranged atintervals along the periphery of the barrel portion main body 10, andthe mud discharging holes 27 are preferably disposed along the peripheryof the barrel portion main body 10 at intervals on a position betweenthe positions on which the drive tooth portions 12 are disposed.

[0050] Because the peripheral portion of the barrel portion main body 10in correspondence with the position provided with the drive toothportion 12 is brought into contact with the inner face of the belt mainbody along with the drive tooth portion, the peripheral portion canexert uniform extension force to the tension member embedded in the beltmain body by providing the mud discharging hole avoiding the portions towhich the drive tooth portions 12 are disposed.

[0051] According to another aspect of the invention, the contact portion17 includes a contact portion 17 a in contact with the belt main body 8having a width corresponding to the root width B of the projection 9 inthe belt width direction and radially outwardly projecting relative toother portion 17 b of the contact portion 17.

[0052] By projecting a part of the contact portion 17 in correspondencewith the root width in the belt width direction of the projection formedto project from the inner face of the elastic crawler (belt main body),the tension member 14 deformed into a polygonal shape can be outwardlypushed at a portion in correspondence with one side of the polygonalshape from an inner face side of the elastic crawler 2, whereby an angleof a corner of the polygon can be increased. As a result, deformation ofthe tension member is further alleviated, whereby exertion of localforce on the tension member can be made as less as possible.

[0053] According to another aspect of the invention, the guide portion19 includes a pair of right and left restricting faces 21 to be broughtinto contact with the opposite sides of the projection 9 in the beltwidth direction for restricting the shift of the projection 9 relativeto the drive tooth portion 12 in the belt width direction.

[0054] With this arrangement, when the elastic crawler and the sprocketfor the crawler belt are shifted from each other in the belt widthdirection, the restricting face is brought into contact with theprojection and further shift is prevented so that the sprocket is hardlydisengagement from the elastic crawler.

[0055] According to another aspect of the invention, each of therestricting faces 21 is inclined so that a clearance from the projection9 increases toward each of opposite ends of the guide portion in thebelt width direction.

[0056] With this arrangement, when soil (mud) or the like entered intothe clearance between the projection and the restricting face, and theprojection and the restricting face is going to be brought into contactwith each other, since the restricting face is inclined, the soil (mud)or the like is hardly brought into press contact with the restrictingface and hardly stuck thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0057]FIG. 1 is a sectional view taken along arrow marks Z-Z in FIG. 12showing a state in which a sprocket for a crawler belt and an elasticcrawler according to the invention are in contact with each other;

[0058]FIG. 2 is a sectional view showing a state in which a sprocket fora crawler belt and an elastic crawler according to the invention are incontact with each other;

[0059]FIG. 3 is a perspective view showing a first embodiment of asprocket for a crawler belt according to the invention;

[0060]FIG. 4 is a partial side view showing a state in which thesprocket for a crawler belt and an elastic crawler in contact with eachother according to the first embodiment;

[0061]FIG. 5 is a perspective view showing a second embodiment of asprocket for a crawler belt according to the invention;

[0062]FIG. 6 is a perspective view showing a third embodiment of asprocket for a crawler belt according to the invention;

[0063]FIG. 7 is a sectional view taken along arrow marks P-P in FIG. 2.

[0064]FIG. 8 is a perspective view showing a fourth embodiment of asprocket for a crawler belt according to the invention;

[0065]FIG. 9 is a plan view showing a fifth embodiment of a sprocket fora crawler belt according to the invention;

[0066]FIG. 10 is a plan view showing a sixth embodiment of a sprocketfor a crawler belt according to the invention;

[0067]FIG. 11 is a plan view showing a seventh embodiment of a sprocketfor a crawler belt according to the invention;

[0068]FIG. 12 is a side view showing an embodiment of an elastic crawlertraveling apparatus according to the invention;

[0069]FIG. 13 is a sectional view showing a state in which a sprocketfor a crawler belt and an elastic crawler of a conventional elasticcrawler traveling apparatus are in contact with each other;

[0070]FIG. 14 is a sectional view showing a state in which a drivenwheel (or rolling wheel) and an elastic crawler of a conventionalelastic crawler traveling apparatus into contact with each other; and

[0071]FIG. 15 is a sectional view taken along arrow marks Q-Q in FIG.13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] The present invention will now be described in detail by way ofthe preferred embodiment thereof illustrated in the attached drawings.

[0073]FIG. 12 shows an example of an embodiment of an elastic crawlertraveling apparatus according to the invention.

[0074] An elastic crawler traveling apparatus 1 according to theinvention is mainly constituted by an elastic crawler 2 formed in ashape of an endless belt by an elastic material of rubber or the like, asprocket 3 for a crawler belt constituting a drive wheel for driving theelastic crawler 2, and a driven wheel 6 and a rolling wheel 7 eacharranged to be in contact with an inner face of the elastic crawler 2 ata predetermined center distance from the sprocket 3 for the crawlerbelt.

[0075] Further, by arranging the sprocket 3 for the crawler belt, thedriven wheel 6 and the rolling wheel 7 respectively at predeterminedcenter distances therebetween, the elastic crawler 2 can circulatinglybe run by being transmitted with driving force by the sprocket 3 for thecrawler belt.

[0076] The elastic crawler 2 is mainly constituted by a belt main body8, a plurality of projections 9 formed to project from an inner face ofthe belt main body 8 and a tension member 14 of a steel cord or the likeembedded at an inner portion of the belt main body 8 for restrictingelongation of the belt main body 8 in a longitudinal direction thereof.

[0077] A plurality of the projections 9 are arranged at constantintervals on the inner face of the belt main body 8 over an entireperiphery in a peripheral direction thereof.

[0078] A valley portion between the projection 9 constitutes an engaginggroove 15 to be engaged with the sprocket 3 for the crawler belt fortransmitting the driven force.

[0079] Further, the tension member 14 is provided for restrictingelongation of the elastic crawler in a longitudinal direction thereofcaused by a force of the sprocket for the crawler belt, the driven wheel6, and the rolling wheel 7 to push to elongate the elastic crawler 2from an inner side thereof (hereinafter, referred to as extendingtension force).

[0080] The tension member 14 is embedded within a constant embeddingwidth in a belt width direction (hereinafter, the direction defines areference direction and is simply referred to as belt width direction)of the belt main body 8.

[0081]FIG. 3 shows a first embodiment of a sprocket for a crawler beltaccording to the invention.

[0082] The sprocket 3 for the crawler belt has substantially a shape ofa star in side view and is constituted by a drive tooth portion 12 to befitted into the engaging groove 15 for transmitting the driving force,and a barrel portion main body 10 for supporting the drive tooth portion12.

[0083] The drive tooth portion 12 is formed in a cylindrical shape to befitted into the engaging groove 15 so as to transmit the driving force.

[0084]FIG. 4 is a partial side view showing a state in which the elasticcrawler is wrapped around the sprocket for the crawler belt according tothe first embodiment.

[0085] The drive tooth portion 12 of the sprocket 3 for the crawler beltis fitted into the engaging groove 15, and the drive tooth portion 12 isin contact with the inner face of the belt main body 8 at a contactportion 17 on the top end portion thereof in view from a side of thebarrel portion main body 10.

[0086] A recessed portion 11 formed between the drive tooth portions 12on the barrel portion main body 10 has a depth for preventing therecessed portion 11 from contacting a projected end portion of theprojection 9.

[0087] Since the recessed portion 11 is formed such as to be preventedfrom contacting the projected end portion of the projection 9, aclearance is produced between the projection 9 and the recessed portion11 in the wrapping state, thereby facilitating discharge of soil (mud)or the like brought into the clearance from the sprocket 3 for thecrawler belt.

[0088] Further, there is formed a shaft insertion hole 25 for mounting adrive shaft for transmitting the driving force at a center of the barrelportion main body 10.

[0089]FIG. 5 shows a second embodiment of a sprocket for a crawler beltaccording to the invention.

[0090] According to the sprocket 3 for the crawler belt shown in FIG. 5,both end portions in a longitudinal direction of the drive tooth portion12, constitute guide portions 19 for restricting lateral shift (shift inthe belt width direction) between the sprocket 3 for the crawler belt(drive tooth portion 12) and the elastic crawler 12 relative to eachother.

[0091] The guide portion 19 is formed with a restricting face 21 forrestricting the lateral shift.

[0092] When the lateral shift occurs, the restricting face 21 is broughtinto contact with the projection 9 thereby restricting further shift ofthe sprocket 3 for the crawler belt.

[0093]FIG. 1 shows a state in which the sprocket 3 for the crawler beltaccording to the second embodiment is brought into contact with theelastic crawler 2.

[0094] As shown by FIG. 1, a contact width (width designated by notationC) of the contact portion 17 of the sprocket 3 for the crawler belt inthe belt width direction (direction indicated by notation X, the same asfollows in other drawings) is made wider than a root width (widthdesignated by notation B) of the projections 9 in the belt widthdirection and is made substantially equal to an embedding width (widthdesignated by notation A) of the tension member 14 in the belt widthdirection.

[0095] Since the contact width C of the contact portion 17 is wider thanthe root width B and substantially equal to the embedding width A of thetension member 14, the sprocket 3 for the crawler belt (or drive toothportion 12) in the wrapped state can transmit uniform force to thetension member 14 disposed within the embedding width A, in other words,extending tension force can be uniformly exerted on the tension member14 disposed within the embedding width A.

[0096]FIG. 6 shows a third embodiment of a sprocket for a crawler beltaccording to the invention.

[0097] According to the third embodiment, the sprocket 3 is constitutedby a pair of barrel portion main bodies 10 in a cylindrical shape(drum), and a drive tooth portion 12 in a rod-like shape providedbetween the main bodies 10 in a sandwiching manner, wherein each ofopposite ends of the drive tooth portion 12 in the longitudinaldirection thereof is integrally connected to each of the main bodies 10on a side edge in the widthwise direction thereof facing its counterpartmain bodies 10.

[0098] A plurality of the drive tooth portions 12 are arranged atconstant intervals along the periphery of the barrel portion main bodies10.

[0099] The barrel portion main body 10 is formed along the peripheralportion thereof with a plurality of mud discharging holes 27 fordischarging soil (mud) or the like brought between the sprocket 3 forthe crawler belt and the elastic crawler 2 in a state where the elasticcrawler 2 is wrapped around the sprocket 3 for the crawler belt.

[0100] The mud discharging holes 27 are disposed at predeterminedintervals along the peripheral direction of the barrel portion main body10.

[0101]FIG. 2 shows a state in which the sprocket 3 for the crawler beltaccording to the third embodiment is brought into contact with theelastic crawler 2.

[0102] As shown by FIG. 2, the contact portion 17 in contact with thebelt main body 8 in the sprocket 3 for the crawler belt includes aportion 17 a at which the drive tooth portion 12 is brought into contactwith the belt main body 8, and side portions 17 b of the barrel mainbody 10 disposed on opposite sides of the portion 17 a.

[0103] In the contact portion 17, the portion 17 a corresponding to theroot width B in the belt width direction of the projection 9 formed toproject from the inner face of the belt main body 8, that is, theportion 17 a to be brought into contact with the belt main body 8 isformed to radially outwardly project relative to other contact portion,that is, the side portions 17 b of the barrel portion main body 10.

[0104] The contact width C of the contact portion 17 in the belt widthdirection is made to be substantially equal to the embedding width A inthe belt width direction of the tension member 14.

[0105] When both of the drive tooth portion 12 and the barrel portionmain body 10 are brought into contact with the elastic crawler 2 in thisway, since the contact width C in the belt width direction of thecontact portion 17 at which the drive tooth portion 12 and the barrelportion main body 10 are brought into contact with the elastic crawler 2substantially equal to the embedding width A of the tension member 14,extending tension force can be uniformly exerted on the tension member14 disposed within the embedding width A.

[0106] Further, as described above, the plurality of mud dischargingholes 27 are formed at predetermined intervals along the peripheralportion of the barrel portion main body 10. More specifically, it ispreferable to form the mud discharging hole 27 at a position of thebarrel portion main body 10 avoiding the contact portion 17, that is, ata portion of the peripheral portion of the barrel portion main body 10in correspondence with an interval between the drive tooth portions 12,in which the predetermined interval refers to the interval between themud discharging holes 27 formed in this way.

[0107]FIG. 7 shows a sectional view taken along arrow marks P-P of FIG.2.

[0108] As described above referring to FIG. 2, since the drive toothportion 12 is formed to project from the barrel portion main body 10,when the drive tooth portion 12 is brought into contact with the beltmain body 8, the projecting drive tooth portion 12 pushes the belt mainbody 8, thereby pushing the tension member 14 in accordance therewith toradially outwardly elongate the tension member 14 from the center of thesprocket 3 for the crawler belt by a pushed amount.

[0109]FIG. 15 shows the wrapping state when the drive tooth portion isnot projected as described above. Comparing FIG. 15 and FIG. 7, a degreeof deformation of the tension member 14 in FIG. 7 is smaller than adegree of deformation of the tension member 14 in the polygonal shape inFIG. 15, and the extending tension force exerted on the tension member14 in the state of FIG. 7 is more uniform than that in the state of FIG.15.

[0110]FIG. 8 shows a fourth embodiment of a sprocket for a crawler beltaccording to the invention.

[0111] The sprocket 3 for the crawler belt according to the fourthembodiment is constituted by sandwiching both left and right sides ofthe sprocket 3 for the crawler belt of the first embodiment with thepair of barrel portion main bodies 10 of the third embodiment.

[0112] When the sprocket for the crawler belt according to the inventionis required larger strength, the sprocket for the crawler belt accordingto the fourth embodiment may be adopted.

[0113]FIG. 9 through FIG. 11 show states of wrapping the elastic crawleraround the sprocket for the crawler belt as explained in the secondembodiment, and an explanation will be given of a relationship ofengaging the drive tooth portion of the sprocket for the crawler beltand the elastic crawler as follows.

[0114]FIG. 9 shows a fifth embodiment of a sprocket for a crawler belt(drive tooth portion) according to the invention.

[0115] In FIG. 9, there is shown a state of bringing the elastic crawlerand the sprocket for the crawler belt (drive tooth portion) into meshwith each other and only the drive tooth portion 12 is shown byimaginary lines of two-dotted chain lines (hereinafter, the same in FIG.10, FIG. 11).

[0116] The drive tooth portion 12 shown in FIG. 9 is mainly constitutedby a driving portion 18 fitted in the engaging groove 15 fortransmitting the driving force to the elastic crawler 2 and the guideportion 19 engaged with the projection 9 in the belt width direction forrestricting shift (lateral shift) in the belt width direction of thesprocket 3 for the crawler belt and the elastic crawler 2 relative toeach other (hereinafter, the same in FIG. 10, FIG. 11).

[0117] The width of the driving portion 18 in the peripheral direction(direction indicated by notation Y) of the belt main body 8(hereinafter, the width in the direction is referred to as peripheraldirection width) is substantially made to be equal to the peripheraldirection width of the engaging groove 15, meanwhile, the peripheraldirection width of the guide portion 19 is made larger than theperipheral direction width of the engaging groove 15.

[0118] With this arrangement, when the elastic crawler 2 and thesprocket 3 for the crawler belt are shifted from each other in the beltwidth direction (when lateral shift is caused), the guide portion 19 isabutted (brought into contact with) to the projection 9 and furthershift of the sprocket for the crawler belt (drive tooth portion 12) canbe restricted.

[0119] Here, the guide portion 19 has a face to be abutted to theprojection 9, which is designated by notation 21 as the restricting facefor restricting the lateral shift. The restricting faces 21 are formedon the guide portions 19 to be engaged with both of each pair ofprojections 9 adjacent in the peripheral direction Y for forming theengaging groove 15.

[0120] It is preferable that each of the restricting faces 21 isprovided to be inclined to so that a clearance from the projection 9increases toward each of opposite ends of the guide portion in the beltwidth direction as shown by FIG. 9.

[0121] With this configuration, since the restricting face 21 isinclined to the direction of the lateral shift (belt width direction),even when the projection 9 abuts the restricting face, soil (mud)brought between the projection 9 and the restricting face 21 is hardlystuck on the restricting face 21.

[0122] Further, in order to restrict the lateral shift between thesprocket 3 and the elastic crawler 2 both in left and right directions,it is necessary to form a left and right pair of the restricting faces21 relative to the center of the drive tooth portion 12 in thelongitudinal direction thereof so as to be disposed on both sides of theprojection 9 in the belt width direction.

[0123]FIG. 10 shows a sixth embodiment of a sprocket for a crawler belt(drive tooth portion) according to the invention.

[0124] According to the sixth embodiment, the restricting faces 21 forrestricting the lateral shift of the elastic crawler 2 and the drivetooth portion 12 relative to each other are provided on the guideportions 19 to be engaged with one of the pair of the adjacentprojections 9 for forming the engaging groove 15.

[0125] Even when the restricting faces 21 are provided to the guideportions 19 in this way, similar to the fifth embodiment, the lateralshift can be restricted by constituting a pair of left and rightrestricting faces 21 relative to the center of the drive tooth portion12 in the longitudinal direction thereof.

[0126]FIG. 11 shows a seventh embodiment of a sprocket for a crawlerbelt (drive tooth portion) according to the invention.

[0127] According to the seventh embodiment, there are provided two rowsof the projections 9 formed to project from the elastic crawler 2 alongthe peripheral direction Y of the belt main body 8.

[0128] The restricting faces 21 of the guide portion 19 according tothis embodiment are formed in a so-to-speak zigzag shape relative to theperipheral direction Y of the drive tooth portion 12. Even when therestricting faces 21 are provided in such a pattern (zigzag shape), thelateral shift can be restricted similar to the fifth and the sixthembodiments since the restricting faces 21 constitute a left and rightpair relative to the center of the drive tooth portion 12 in thelongitudinal direction thereof.

[0129] When the elastic crawler traveling apparatus explained with FIG.12 provided with the sprockets for the crawler belt havingcharacteristics explained in the first through the seventh embodimentsas described above is driven, the tension member embedded in the elasticcrawler can be prevented from being exerted with local force as much aspossible, whereby the elastic crawler traveling apparatus can obtain theelastic crawler having prolonged service life.

[0130] According to the invention explained in details as describedabove, there is provided an elastic crawler traveling apparatus capableof reducing exertion of local force on the tension member embedded inthe elastic crawler as less as possible and a sprocket for the crawlerbelt used in the elastic crawler traveling apparatus.

[0131] It should be noted that the invention is not limited to theembodiments explained above but can be modified variously as follows.

[0132] The elastic crawler traveling apparatus according to theinvention is not limited to the apparatus explained in reference to FIG.12 but may be any apparatus so far as the apparatus is provided with anelastic crawler formed in a shape of an endless belt by an elasticmaterial of rubber or the like, a sprocket for a crawler belt arrangedto be brought into contact with an inner face of the elastic crawler, adriven wheel, and a rolling wheel.

[0133] A pattern of forming the restricting face formed at the guideportion for restricting the lateral shift is not limited to the patternsexplained in the fifth through the seventh embodiments but may be anypattern so far as the pattern constitutes a left and right pair relativeto the center of the drive tooth portion in the longitudinal directionthereof

[0134] Further, although according to the seventh embodiment, two rowsof the projections 9 are formed to project from the inner face of theelastic crawler along the peripheral direction of the belt main body,the number of rows of the projection 9 is not limited to one or two buteven when three or more rows (plural rows) thereof are formed, the drivetooth portion of the sprocket for the crawler belt according to theinvention can be engaged therewith.

[0135] When two or more rows of the projections are constituted asdescribed above, the drive tooth portion having the guide portions maybe provided on the sprocket for the crawler belt such that the guideportions are engaged with the projections of respective rows.

[0136] The sizes and the number of the mud discharging holes 27 formedalong the peripheral portion of the barrel portion main body 10 may bevaried in consideration of strength or the like of the drive portionmain body 10.

[0137] The constitution of the tension member embedded in the elasticcrawler is not limited to the constitution in which a plurality oftension members formed of steel cord or the like are embedded within theembedding width but, for example, the tension member may be a member ofa strip-like shape having a constant width.

What is claimed is:
 1. An elastic crawler traveling apparatus (1)including an elastic crawler (2) in a shape of an endless belt formed ofan elastic material of rubber or the like; a sprocket (3) for a crawlerbelt arranged to be brought into contact with an inner face of theelastic crawler (2); a driven wheel (6); and a rolling wheel (7), theelastic crawler (2) comprising a belt main body (8); a plurality ofprojections (9) formed to project at intervals therebetween along aperipheral direction of the elastic crawler on an inner face of the beltmain body (8); and a tension member (14) of a steel cord or the likeembedded at an inner portion of the belt main body (8) for restrictingelongation of the belt main body (8), the sprocket (3) comprising acontact portion (17) to contact the belt main body (8), the contactportion (17) having a contact width (C) which is greater than a rootwidth (B) of the projection in a belt width direction of the elasticcrawler.
 2. An elastic crawler traveling apparatus (1) including anelastic crawler (2) in a shape of an endless belt formed of an elasticmaterial of rubber or the like; a sprocket (3) for a crawler beltarranged to be brought into contact with an inner face of the elasticcrawler (2); a driven wheel (6); and a rolling wheel (7), the elasticcrawler (2) comprising a belt main body (8); a plurality of projections(9) formed to project at intervals therebetween along a peripheraldirection of the elastic crawler on an inner face of the belt main body(8); and a tension member (14) of a steel cord or the like embedded atan inner portion of the belt main body (8) for restricting elongation ofthe belt main body (8), the sprocket (3) comprising a contact portion(17) to contact the belt main body (8), the contact portion (17) havingcontact width (C) which is substantially equal to an embedding width (A)of the tension member (14) in a belt width direction of the elasticcrawler.
 3. The elastic crawler traveling apparatus (1) according toclaim 1, wherein the sprocket (3) for the crawler belt comprises aplurality of drive tooth portions (12) to be engaged with theprojections (9); and a barrel portion main body (10) integrally formedwith the drive tooth portions (12); and wherein the barrel portion mainbody (10) is formed with a recessed portion (11) on a portion thereofbetween the drive tooth portions (12) so as to prevent a projected endportion of the projection (9) and the barrel portion main body (10) frombeing brought into contact with each other.
 4. The elastic crawlertraveling apparatus (1) according to claim 2, wherein the sprocket (3)for the crawler belt comprises a plurality of drive tooth portions (12)to be engaged with the projections (9); and a barrel portion main body(10) integrally formed with the drive tooth portions (12); and whereinthe barrel portion main body (10) is formed with a recessed portion (11)on a portion thereof between the drive tooth portions (12) so as toprevent a projected end portion of the projection (9) and the barrelportion main body (10) from being brought into contact with each other.5. The elastic crawler traveling apparatus (1) according to claim 1,wherein the sprocket (3) for the crawler belt comprises a plurality ofdrive tooth portions (12) to be engaged with the projections (9); and abarrel portion main body (10) integrally formed with the drive toothportions (12); wherein each pair of the projections (9) adjacent in theperipheral direction of the elastic crawler form a valley portiontherebetween as an engaging groove (15) to be engaged with the drivetooth portion (12); and wherein the drive tooth portion (12) comprises adriving portion (18) to be engaged with the engaging groove (15) in theperipheral direction of the elastic crawler; and a guide portion (19) tobe engaged with the projection (9) in the belt width direction forrestricting a shift of the drive tooth portion (12) and the projection(9) in the belt width direction relative to each other.
 6. The elasticcrawler traveling apparatus (1) according to claim 2, wherein thesprocket (3) for the crawler belt comprises a plurality of drive toothportions (12) to be engaged with the projections (9); and a barrelportion main body (10) integrally formed with the drive tooth portions(12); wherein each pair of the projections (9) adjacent in theperipheral direction of the elastic crawler form a valley portiontherebetween as an engaging groove (15) to be engaged with the drivetooth portion (12); and wherein the drive tooth portion (12) comprises adriving portion (18) to be engaged with the engaging groove (15) in theperipheral direction of the elastic crawler; and a guide portion (19) tobe engaged with the projection (9) in the belt width direction forrestricting a shift of the drive tooth portion (12) and the projection(9) in the belt width direction relative to each other.
 7. The elasticcrawler traveling apparatus (1) according to claim 1, wherein thesprocket (3) for the crawler belt comprises a drive tooth portion (12)in a rod-like shape to be engaged with the projection (9); and a pair ofbarrel portion main bodies (10) having a cylindrical shape andsandwiching the drive tooth portion (12) therebetween; and wherein thebarrel main body (10) defines along its peripheral portion a pluralityof mud discharging holes (27) for discharging soil, mud or the like. 8.The elastic crawler traveling apparatus (1) according to claim 2,wherein the sprocket (3) for the crawler belt comprises a drive toothportion (12) in a rod-like shape to be engaged with the projection (9);and a pair of barrel portion main bodies (10) having a cylindrical shapeand sandwiching the drive tooth portion (12) therebetween; and whereinthe barrel main body (10) defines along its peripheral portion aplurality of mud discharging holes (27) for discharging soil, mud or thelike.
 9. The elastic crawler traveling apparatus (1) according to claim1, wherein the contact portion (17) includes a contact portion (17 a)having a width corresponding to the root width (B) of the projection (9)in the belt width direction, and radially outwardly projecting relativeto other portion (17 b) of the contact portion (17).
 10. The elasticcrawler traveling apparatus (1) according to claim 2, wherein thecontact portion (17) includes a contact portion (17 a) having a widthcorresponding to the root width (B) of the projection (9) in the beltwidth direction, and radially outwardly projecting relative to otherportion (17 b) of the contact portion (17).
 11. The elastic crawlertraveling apparatus (1) according to claim 5, wherein the guide portion(19) includes a pair of right and left restricting faces (21) to bebrought into contact with opposite sides of the projection (9) in thebelt width direction for restricting the shift of the projection (9)relative to the drive tooth portion (12) in the belt width direction.12. The elastic crawler traveling apparatus (1) according to claim 6,wherein the guide portion (19) includes a pair of right and leftrestricting faces (21) to be brought into contact with opposite sides ofthe projection (9) in the belt width direction for restricting the shiftof the projection (9) relative to the drive tooth portion (12) in thebelt width direction.
 13. The elastic crawler traveling apparatus (1)according to claim 11, wherein each of the restricting faces 21 isprovided to be inclined to so that a clearance from the projection 9increases toward each of opposite ends of the guide portion in the beltwidth direction.
 14. The elastic crawler traveling apparatus (1)according to claim 12, wherein each of the restricting faces 21 isprovided to be inclined to so that a clearance from the projection 9increases toward each of opposite ends of the guide portion in the beltwidth direction.